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A. E. HAGUE. MACHINE swlTcHlNG TELEPHONE SYSTEM.

APPLICATION FILED OCI'. 30. I9ll.

Patented Muy (3, 1919.

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APPLICATION FILED DCT. 30, 1911.

Patented May (L 1919.

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A. E. HAGUE. MACHINE SWITCHING TELEPHONE SYSTEM.

APPLICATION FILED OCT. 30. I9Il.

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UNITED sTaTEs PATENT oEFioE..

ALFRED E. HAGUE, 0F NEW YORK., N. Y., ASSIGNOR T0 WESTERN ELECTRICCOMPANY,

. INCORPORATED,

0F NEW YORK, N. Y., A. CORPORATICN 0F NEW YORK.

MACHINE-SWITCHING TELEPHONE SYSTEM.

Specication of Letters Patent.

Patented May 6, 1919.

Application iled October 30, 1917. Serial No. 199,284.

of New York, have invented certain new and useful Improvements inMachine- Switching Telephone Systems, of which the following is a full,clear, concise, and exact description.

This invention relates to machine switch'- ing telephone systems and hasfor an object the prevention of false setting or actuation of selectiveswitches through the accidental transmission of a single impulse.

It has often happened that a subscriber by carelessly handling histelephone instrument has so jarred or moved his switchhook as to cause amomentary break in his line circuit, thereby transmitting an impulsesimilar to one caused' by the proper manipulation of the dial switch.'If this happens just after the line lfinder switch has functioned orafter a selector switch has seized a trunk leading to another selectorswitch it results in the establishment of a wrong connection, since thenext selector will be actuated to set its brushes on the lirst group ofcontacts.

In certain commercial automatic telephone systems, another unstandardcondition often arises whereby a subscribers bell is rung when, as amatter of fact, no connection was intentionally extended to his line.This is due to the fact that a subscriber has established a partialconnection and has abandoned the call before sending the last digit ofthe call number. In this case a connector switch has been actuated inits primary movement only. If now, the call is abandoned, a singleimpulse to actuate the connector switch in its secondary movement willbe transmitted before the releasing mechanism can come into play, withthe result that the brushes of the connector switch are set on theterminals of the first line of the selected group and very often ringingcurrent will be momentarily'transmitted to that line before the brushesare removed. Such an unstandard condition 1s a source of great annoyanceto the subscribers and a scheme for its prevention constitutes a usefulimprovement in the art.

"Accordingly a feature of the present invention the provision of meansfor absorbing a singlel impulse which would ordinarily actuate aselective switch in its directed movement. According to this feature theimpulse mechanism for setting the switches in such a system is arrangedto send an extra impulse in each series of impulses, representing thecharacters of the designation of a called line, and means are providedto render such extra impulse ineffective.

This means is an improvement over other schemes heretofore proposed,being specifically the addition to the ordinary circuit of a'singlerelay with a single winding.

The drawings are a diagrammatic representation of a telephone systemembodying the present invention. Figure 1 represents a callingsubscribers line and a line -finder switch; Fig. 2, placed to the rightof Fig. 1, represents the connection eX- tended to a selector switch;and Fig. 3, placed to the right of Fig. 2, represents the connectionextended to a connector switch and thence to a called subscribers line.

The invention will be more readily understood from a detaileddescription of the operation.

Upon the removal of the receiver at sub station A, line relay 100 isenergized. In attracting its left armature it creates a callingcondition upon the multiple 101 of substation A in the finders in whichsuch line appears. In attracting its right armature, it energizes relay102 to start a line finder in search of the calling line. Relay 102, inattracting its upper armature, locks itself to conductor 103,independently of the armature and back contact of relay 104, and inattracting its lower armature, applies ground to multiple segment '105individual to the group of lines to which substation A belongs, and alsocloses the circuit-of the primary magnet PM of the line finder asfollows: ground7 lower armature and front contact of relay 102,conductors 10G, 107, armature and back contact of relay 108. conductor109, side-switch arm 110 and its first contact. armature and backcontact of magnet PM, magnet PM, free pole of battery. This-magnet makesand breaks its own circuit, thus rotating fthe inder brush shaft 153.The attraction of the lower armature of relay 102 also closes a. circuitfor relay 111 in parallel with that traced for magnet PM: ground. lowerarmature and front contact of relay 1027 conductors 10,6 and 107,

armature and back contact ductor 113, relay 111, free pole of battery.Relay 111 connects the group brush 114 to the escape magnet ESC. At thistime, however, the escape magnet does not operate, since it is shuntedover the path traced, including the armature and back contact of magnetPM. Magnet PM energizes in the circuit traced and near the end of itsstroke opens the shunt about the escape-magnet, at which time the brush114 is in contact with i grounded group segment 105, and becomes tact101, brush energized over the following circuit: free pole of battery,magnet PM, magnet ESC, conductor 115, left armature and front contact ofrelay 111, conductor 116, brush 114, segment 105, to ground at the lowerarmature and front contact of relay 102. The escape magnet isconstructed to release the side switch from position 1 to position 2upon its energization. In position 2, the escape magnet is maintainedenergized over the following` circuit: free pole of battery, magnet PM,magnet ESC, armature and back contact of relay 117, arm 118 and itssecond contact, conductor 119, conductor 200, left armature and backcontact of relay 202 to ground. In position 2, arm 110 closes thefollowing circuit for magnet SM t0 ste the positioned finder brushes120, 121. 122 over the multiples 123, 124 and 101, of the group to whichsubstation A belongs: free pole of battery, magnet SM, its amature andack contact, armature and contact of magnet ESC, arm 110 and its secondcontact, con-- ductor 109, to ground at the lower armature and frontcontact of relay 102. When the test brush 122 reaches the multiple 101of substation A, the following` circuit is closed to operate test relay.117 to stop the move.- ment of the line finder: free pole of battery,resistance 125, left armature and front contact of relay 100, conductor126, multiple 101, brush 122, relay 117 to ground. Relay 117 opens thecircuit traced for magnet ESC, vwhich becomes denergized. and inretracting its armature, opens the .circuit of magnet SM to sto thefinder on the calling line terminals. Magnet ESC, in denergizing,releases the side switch into position 3. In position 3 arm 118energizes the cutoff relay 127 over the following circuit: free pole ofbattery, winding of relay 127, con- 122, arm 118 and its third contact,conductors 119, 200, left armature and back contact of relay 202 toground. Relay 127, in operating, de'energizes relay 100. The retractionof the left armature of relay 100 removes the calling condition frommultiples 101 of substation A, and the re traction of the right armaturedenergizes relay 102. Relay 102, in retracting its lower armature,removes ground from starter wire 107 and restores the continuity of theinstarter wire 129, 107. Relay 117 is shunted of relay 108, conandlbecomes inert, due to the application of the direct ground to the brush122, referred to.

In position 3, the following circuit, including the calling line, isclosed for the impulse relay 131: free pole of battery, right windin ofrelay 131, conductor 132, arm 133 an its third contact, conductor 134,arm 135 and its third contact, brush 121, terminal 124, through thetelephonie apparatus at substation A, terminal 123, brush 120, arm 136and its third contact, conductors 137, 138, left winding of relay 131,ground. Relay 131, in operating, energizes a slow release relay 139.Relay 139, in attracting its right armature, interposes a break in thecircuit of finder release magnet RM. In attracting its leftarmatureythis relay closes the following circuit toenergize a slowrelease relay 202 (Fig.2) ground, left armature and front contact ofrelay 139, conductor 140, first selector side-switch arm 201, relay 202,free pole of battery. Relay 202, in attractingits left armature, closesthe following circuit for relay 203, which. in operating, connects theprimary magnet PM to the back contact of the stepping relay 131: leftarmature and front contact of relay 202, conductor 204, right armatureand back contact of relay 205, back contact and armature of releasemagnet RM, winding of relay 203, to free pole of battery.

When the finder side switch moves into position 3, a distinctive tone istransmitted over the following circuit, to the calling 100 line toindicate to the calling party that the central office apparatus is readyto receive impulses; free pole of battery, secondary winding of tonesource 206, relay 207, left armature and back contact of relay- 205, 105arm 208 and its first contact. lower armature and back contact. of relay209. conductor 210, right winding of relay 211, free pole of battery.This tone is transmitted by induction through the windings of relay 211H0 to the calling line over the following circuit: ground, left windingof relay 211. conductor 212, upper talking conductor 213. condenser 214,conductor 137, arm 136 and its third contact, brush 120. terminal 123.115 through the telephonie apparatus at substation A, terminal 124,brush 121, arm 135 and its third contact, conductor 134. arm 133 and itsthird contact, right winding of relay 131. free pole of battery.

The called party now operates his sender S to transmit the first digitof the wanted number. In returning to normal the sender interrupts thecircuit traced a number of times. corresponding to the digit. in 125Volved. It should be noted` however. that the sender is arranged totransmit one more impulse in each case than is necessary for the propersetting of the switches.

Upon the first retraction of t-he armature 130 tact of relay 131, rightarmature and front contact of relay 139, arm 142 and its third contact,conductor 143, back contact and left-hand armature of relay 211, windingof slow release relay 209, armature and back contact of' relay 215,resistance 216, free pole of battery. Relay 209 is energized in thiscircuit and upon attracting its upper armature provides a circuit fromground, upper armature and front contact of relay 209, winding of relay215, resistance 216, free pole of battery, for the energizatio-n ofrelay 215 which, however, is not effective 'tures and denergize relay215.

into operative relation until the cessation of this first impulse due tothe reduced potential on the winding of relay 215. When relay 131 againattracts its armatures relay 215 becomes energized, and by attractingits armature prepares a circuit for the succeeding proper number ofimpulses to the stepping magnet. If this impulse is an accidental onethen in a short space of time relay 209 will retract its arma- If,however, this lirst impulse is followed by a train of like impulsesvthecircuit from the back contact of relay 131 will be extended by theaction of relay 215 from the Winding of relay 209 through the armatureand front contact of relay 215 to arm 217 and its first contact,conductor 218, left armatureand front contact of relay 203, winding ofprimary magnet PM to free pole of battery, Magnet PM in response tothese impulses steps the selector brushes 219, 220 and 221 with thedesired group of trunks.

Relay 2,09, being slow to release its 'armature, is maintained energizedduring the transmission of the impulses. In attracting its armature,this relay closes the following circuit for a relay 207: ground, lowerarmature and front contact of relay 209, arm 208 and its first contact,left armature and back contact of relay 205, relay 207, secondarywinding of tone source 206, free pole of battery. Relay 207, inoperating, closes the following circuit for the escape magnet 222 of thefirst selector, which magvnet isconstructed to release the side switchfrom position to position upon its deenergization:l free )ole ofbattery, magnet 222, arm 223, conductor 224, spring 225 and armature ofrelay 207 to ground. 'When the sender S restores and maintains relay 131energized, relays 209 and 215, after a slight interval, becomedenerrized, opening the circuit of relay 207, w ich, in deenergizing,opens the circuit of the escape magnet 222, which, in releasing itsarmatures, passes the side switch to position 2 to initiate the trunkhunting operation.

ln position 2, escape magnet 222 is again energized over the followingcircuit: free pole of battery, magnet 222, arm 223 and its secondcontact, spring 226, now closed to its lower contact, to ground. Magnet222, in attracting its armature, closes a self-inter rupting circuit forthe secondary stepping magnet SM of the first selector: free pole ofbattery, magnet SM, its armature and back contact, armature and frontcontact of magnet 222, arm 227, armature and contactof first selectorrelease magnet RM, right armature and back contact of relay 205,conductor 204, left armature and front contact of relay 202 to ground.Magnet SM thus steps brushes 219, 220 and 221 over the selected group inSearch of an idle trunk. Test multiples 228 of busy trunks are grounded,as will hereinafter appear. Upon the first secondary step ofthe brushes,contact 226 is opened and the escape magnet is dependent for itscontinued energization upon the grounded test terminals 228 of busytrunks. When the first idle trunk is reached, the ungrounded conditionof its test multiple 228 causes the denergization of the escape magnet,which opens the stepping circuit, thus stopping the selector upon suchtrunk and in denergizing passes the side switch to position 3.

In position 3 ground is supplied to the test multiples 228 of the seizedtrunk over the Jfollowing circuit: brush 221, conductor 231, arm 232 andits third contact, right armature and front contact of relay 202 toground. The application of this ground en ergizes a relay 300 in theconnector (Fig. 3), which, in attractingits outer right armature,connectsprimary magnet P2M2 of the connector to the upper talkingconductor 301 to receive the tens impulses, and in attracting its leftarmature, interposes a break in the circuit of the connector releasemagnet R2M2. The calling party now operates his sender S to transmit thetens digit of the wanted number.

Upon the first retraction of the armature of stepping relay 131 therelay 209 is energized, as before described. Upon the succeedingattraction of the armature of relay 131 relay 215 is energized toprepare a circuit for the succeeding proper number of impulses. Uponeach succeeding retraction of the armature of the stepping relay 131, animpulse is transmitted over the followin4 circuit to the primarystepping magnet P2Mg of the connector: armature of relay 131, nowgrounded, and its back contact, right armature and front contact ofrelay 139, arm 142 and its third Contact, conductor 143, left armatureand back contact of relay 211, relay 209, armature and front contact ofrelay 215, arm 217 and its third contact, conductor 233, arm 146 and itsthird contact` conductor 234, brush 219, terminal 230, conductors 301,302, outer armature and lfront contact of relay 300, arm 303 and itsfirst contact, magnet P2M2, free pole of battery. Magnet P2M2 thus stepsthe brushes 304, 305, 306 into operative relation with the group ofterminals containing those of the wanted line 307, 308 and 309.- Theslow release relay 209 in the circuit traced for the primary magnetremained energized during the transmission of the impulses. Inattracting its armature, this relay closes the following circuit for theescape magnet 310 of the connector, which releases the connector sideswitch from position to position upon its denergization: ground,armature and front contact of relay 209, arm 208 and its third contact,conductor 235, arm 149 and its third contact, conductor 150, brush 220,terminal 229, conductors 311 and 312, arm 313 and its first contact,armature and back contact of relay 314, escape magnet 310, free pole ofbattery. When the sender restores and maintains impulse relay 131energized, the slow relay 209, after a slight interval, becomes inert,opening the circuit traced for the escape magnet 310, which, inreleasing its armatures, passes the connector side switch to position 2.

In position 2, arm 303 substitutes the secondary magnet S2M2 for theprimary magnet P2M2 in the stepping circuit. The calling party nowoperates his sender S to transmit the units digit of the Wanted number.Upon the first retraction of the armature of relay 131, relay 209 isenergized, as before described. Upon the next attraction of the armatureof relay 131, the relay 215 is energized and thereafter, upon eachretraction of the armature of relay 131, an impulse is transmitted overthecircuit traced to the side-switch arm 303, thence to the secondarymagnet S2M2, free pole of battery, and as before, the slow relay 209, inattracting its lower armature, energizes the con -nector escape magnet310 over side-switch arm 313, now by way of its second contact. Themagnet S2M2 steps the brushes 304, 305, 300 into engagement with themultiples 307 308 and 309 of the desired line. If the line is busy itstest terminal 309 will be grounded over a brush 306, arm 316 and itsthird contact, and the left grounded armature of the relay 315, or sucharm and its fourth contact and the right-hand low-resistance winding ofthe relay 315 to ground of some other connector switch. In such event,the left.-

4hand high-resistance winding of relay 315 of the testing connector isshunted and the relay does not attract its armatures.

In passing out of position 2.` connector side-switch arm 317 opens thecircuit of relay 300. This relay thereupon becomes inert, and inretracting its left armature. closes the circuit of connector releasemagnet R2M2, as follows: free pole of battery, magnet R2M2, conductor318, left. armature and back contact of relay 300, primary offnormalcontact 319 to ground. The release magnet in energizing restores theconnector to its normal position and also restores the side switch.Before contact 319 opens, however, as the brush shaft is restored,contact 320 closes, which results in a locking circuit being providedfor magnet RgM2 as follows: free pole of battery, magnet R2M2. leftarmature and back contact of relay 300, conductor 321, contact 320,resistance 322, conductor 323, right armature and front contact ofmagnet RQMQ. release conductor 325. tere minal 22S, .brush 221,conductor 231, arm 232 and its third contact, right armature and frontcontact of relay 202 to ground. Magnet RZM. at its left armature andfront contact, closes the following circuit to produce a busy tone inthe calling line to indicate to the calling party that the line desiredis occupied: ground. secondary winding of source of busy tone current326. left armature and front contact of magnet RQML. arm 327 and itsfirst contact, condenser 323` arm 329 and its first contact, conductors330'and 311. terminal brush 220. conductor 150. arm 149 and its thirdcontact. conductor 235, arm 20S and its third contact. armature and backcontact of relay 209. (onductor 210, right winding of relay 211. freepole of battery. An induced current is crcated in the secondary Windingof relay 211 included in the calling circuit. This circuit is the sa'meas that traced for the dial tone. The calling party. upon hearing thisbusy tone, replaces his receiver. The replacement of the receiverdenergizes relay 131, which in reti-acting its armature, opens thecircuit of slow relay 139. This relay after a slight interval releasesits armatures. the retraction of the right armature closing the circuitof finder release magnet RM as follows: free pole of battery, magnet RM.conductor 151, right armature and back contact of relay 111, conductor152, right armature and back contacts of relays 139. 131, contact PON toground. The release magnet, in addition to restoring the finder brushshaft 153, alsov restores the Side switch. The retraction of the leftarmature of relay 139 de'e'nergizes relay 202. Relay 202, in retractingits left armature, opens the circuit of relay 203, which relay, inretracting its right armature, closes the circuit of first selectorrelease magnet RM as follows: free pole ot' battery, magnet. RM, rightarmature and back contact of relay 203, contact PO. to ground. MagnetRM. in addition to restoring the selector brush shaft, also restores theside switch. lVhen the shaft reaches its normal position, contact POopens and denergizes the magnet RM. The retraction of the right armatureof rela y 202 removes ground from conductor 231. which results in thcdecnergization of con nector release magnet R2M2. The apparatus is nowall restored.

Assuming the selected line to be idle, full potential is present uponthe multiple 309 thereof, and the test relay 315 becomes energized overits left-hand high resistance winding in the third position of the sideswitch. This circuit is as follows: ground, left winding of relay 315,arm 316 and its third contact, brush 306, terminal 309, cut-olf relay ofthe selected line, free pole of battery. Both the cut-off relay and therelay 315 become energized in this circuit, the former removing thecontrol of the line relay from the selected line in the well-lmownmanner, and the latter connecting the test multiples 309 directly toground over its left armature to cause the selected line `to teSt busyto other connectors. The attraction of the right armature. of relay 315energizes a slow relay 331'over the followingr circuit: free pole ofbattery, relay 331, arm 332 and its third contact, right armature andfront contact of relay 315, right-hand low resistance winding of relay315. to ground. Relay 331, in attracting its armature. closes a lockingcircuit for relay 300 as follows: free pole of battery. relay 300, itsinner right armature and front contact. conductor 333, right armatureand front contact of relay 331 to the grounded third wire 325. Thiscircuit is closed before the circuit including the arm 317 and itssecond contact is opened. as the side switch passes out of position 2.Thus the relay 300 holds its left armature attracted to lnaintain theconnector release circuit open. In parallel with the relay 331. theescape magnet 310 is energized to apply ringing current to the selectedline. *The ringing circuit is as follows: free pole of generator 334,ringing cutoff relay 314. inner armature and front contact of magnet310, arm 335 and its third contact. brush 305. terminal 308, bell 336,

terminal 307 brush 304. arm 337 and its third contact. outer armatureand frontcontact of magnet 310. to ground. A portion of the ringingcurrent flows over the following circuit to indicate by a characteristictone to the calling party that the selected line is being signaled: freepole of generator 334. relay 314. inner armature and front contact ofmagnet 310, conductor 338. arm 327 and its third contact, condenser 328.arm 329 and its third contact. conductors 330. 311. terminal 229. brush220. conductor 150. arm 149 and its third contact, conductor 235, arm

208 and its third contact, lower armature and back 'contact of relay209. right-hand winding of relay 211, free pole of battery. This tone istransmitted by induction through the windings of relay 211 to thecalling line, as before described.

When the called party removes his receiver, marginal ringing cut-offrelay 314 becomes energized, opening the circuit of escape magnet 310which, in denergiziug, passes the side switch to position 4. In position4 arm 316 connects the test multiples 309 to ground through the lowresistance right-hand winding of test relay 315 to maintain such linebusy. Arm 332 in lpassing out of position 3, opens the circuit of slowrelay 331. Before 'this relay retracts its right armature, however. arm317 reaches position 4 and connects release relay 300 to the groundedthird conductor 325 to prevent premature release. The arm 329 reachesits fourth contact before the left armature of relay 331 is retracted,which results in an impulse being transmitted over the following circuitto energize the called supervisory relay 211: ground, left armature andfront contact of relay 331, arm 329 and its fourth contact, conductors330. 311. terminal 229, brush 220. conductor 150. arm 149 and its thirdcontact. conductor 235. arm 208 and its third contact. lower armatureand back contact of relay 209. conductor 210. right winding of relay211. free pole of battery. Relay 211 in attracting its right armature.closes the following circuit for the first selector escape magnet 222:ground. right armature and front contact of said relay, conductor 236,arm 223 and its third contact, magnet 222. free pole of battery. Whenthe irnpulse ceases and relay 211 retracts its right armature. theescape magnet in releasing its armatures. passes the side switch toposition 4. in which position the called supervisory relay 211 i'senergized over the called line circuit as follows: free pole of battery,right winding of relay 211. conductor 210. lower armature and backcontact of relay 209. arm 208 and its fourth contact. conductor 235, arm149 and its third contact. conductor 150, brush 220. terminal 229.conductor 311. arm 335 and its fourth contact, brush 305. terminal 308.through the telephonie apparatus at substation B, terminal 307. brush304, arm 337 and its fourth contact. conductor 301. terminal 230. brush219, Iconductor 234, arm 146 and its third contact, conductor 233. arm217 and its fourth contact. arm 237 and its fourth contact. conductor212. left winding of relay 211, to ground. Relay 211 in holding its leftarmature attracted. permanently interposes a break in the impulsecircuit to prevent the calling party from thereafter transmittingimpulses t0 the magnets, and in holding its right armature attracted,closes a substitute circuit for slow rela-y 202 as follows: ground.right armature and front contact of relay 211, conductor 236. arm 201and its fourth contact, relay 202. free pole of battery. Since relay 202controls the release of the first selector and connector as described.-the release of those switches is now controlled by the called party.

The parties may now converse. talking current being supplied to thecalling line 13 ico over the windings of relay 131 and to the calledlilie over the windings of relay 211.

Upon the termination of the conversation and the replacement of thereceiver b v the calling party, the finder is released as alreadydescribed. The replacement of the receiver by the called partydenergizes relay 211, which, in retlacting its right armature, opens thecircuit of relay 202. The retractioli of the left armature of this relaydeenergizes relay 203 as described in colinection with a busy call, thedenergization of this relay causing the release of the iirst selector.The retraction of the right armature of relay 202 removes grollnd fromthe third wire 9.31, with the result that relay 300 becomes inert, andat its left armature and back contact closes the circuit of releasemagnet H2M2 of the connector as described in connection with a busycall.

Other features, ilicluding the passing of the nder side-switch arms intothe fourth yposition under certain conditions, form no part of thepresent invention and will not be described.

That is claimed is:

4 1. In a telephone system, telephone lines, selective switches forinterconnecting said lilies. a. circuit for the transmission ofimpulses, a rela)v ill series with said circuit responsive to saidimpulses, aiid a second relay responsive to the actuation of said firstrelay at the cessation of a siligle impulse over said circuit forclosing said circuit to said switches.

2. In a telephone system, selective switches for interconnectingr saidlilies, a circuit for the transmission of impulses, a slow7 releasingrelay in series with said circuit, a second relay responsive to theactuation of said slow releasing relay for telephone lines,

closing said circuit to said switches, and means for preventing theenergization of said second relay during the transmission of the. firstof a series of said impulses.

3. In a telephone system telephone lines, selective switches forinterconnecting said lilies including actuating means responsive tocurrent ilnpulses for moving said switches to their successive operativepositions and means for controlling said actuating means, a callingdevice for sending series of impulses to said actuating means, saiddevice being arranged to send an impulse in each series additional tothose required to operate said actuating means, a circuit for thetransmission of said impulses, a slow releasing relay ill series withsaid circuit for controlling said means for controlling said actuatingmeans, a second relay responsive to the actuation of said slow releasingrelay for extending said circuit to said actuating means, and means forpreventing the energization of said second relay during the transmissionof said additional impulse.

l. In a telephone syste-ln, telephone lines, selective switches forinterconnecting said lilies, calling devices for setting said* switches,each arranged to selid one more impulse than is necessary for the propersetting of said switches, a pair of relays for preparing and maintaininga circuit for the transmission of impulses to said switches, said relaysbeing arranged to close said circuit at the end of the first impulsefrom said calling devices, one of said relays being also arranged tocontrol said switches.

In witness whereof, I hereunto subscribe -my name this 24th day ofOctober A. D.,

ALFRED E. HAGUE.

